National & International

‘Biodegradable’ plastic bag survives three years at sea

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Plastic bags that claim to be biodegradable were still intact and able to carry shopping three years after being exposed to the natural environment, according to the Guardian.

The research for the first time tested compostable bags, two forms of biodegradable bag and conventional carrier bags after long-term exposure to the sea, air and earth. None of the bags decomposed fully in all environments.

The compostable bag appears to have fared better than the so-called biodegradable bag. The compostable bag sample had completely disappeared after three months in the marine environment but researchers say more work is needed to establish what the breakdown products are and to consider any potential environmental consequences.

Researchers from the University of Plymouth’s International Marine Litter Research Unit say the study – published in the journal Environmental Science and Technology – raises the question of whether biodegradable bags can be relied on to offer a sufficient rate of degradation as a solution to the problem of plastic litter.

Imogen Napper, who led the study, said: After three years, I was really amazed that any of the bags could still hold a load of shopping. For biodegradable bags to be able to do that was the most surprising.

When you see something labelled in that way, I think you automatically assume it will degrade more quickly than conventional bags. But, after three years at least, our research shows that might not be the case.”

About half of plastics are discarded after a single use and considerable quantities end up as litter.

Image: National Geographic

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